On Fri, 2018-07-27 at 09:48 -0700, Nathan Harold wrote: > We (Android) are very interested in removing the restriction for 32- > bit userspace processes accessing xfrm netlink on 64-bit kernels. > IPsec support is required to pass Android conformance tests, and any > manufacturer wishing to ship 32-bit userspace with a recent kernel > needs out-of-tree changes (removing the compat_task check) to do so. Glad to hear - that justify my attempts more :) > That said, it’s not difficult to work around alignment issues > directly in userspace, so maybe we could just remove the check and > make this the caller's responsibility? Here’s an example of the > workaround currently in the Android tree: > https://android.googlesource.com/platform/system/netd/+/refs/heads/ma > ster/server/XfrmController.h#257 We've kinda same workarounds in our userspace.. But I don't think reverting the check makes much sense - it'll make broken compat ABI in stone. If you're fine with disgraceful hacks and just want to get rid of additional non-mainstream patch - you can make 64-bit syscalls from 32- bit task (hint: examples in x86 selftests). > We could also employ a (relatively simple) solution such as the one > above in the uapi XFRM header itself, though it would require a > caller to declare the target kernel ABI at compile time. Maybe that’s > not unthinkable for an uncommon case? Well, I think, I'll rework my patches set according to critics and separate compat xfrm layer. I've already a selftest to check that 32/64 bit xfrm works - so the most time-taking part is done. So, if you'll wait a week or two - you may help me to justify acception of mainstreaming those patches. > On Fri, Jul 27, 2018 at 7:51 AM, Dmitry Safonov <dima@xxxxxxxxxx> > wrote: > > On Fri, 2018-07-27 at 16:19 +0200, Florian Westphal wrote: > > > Dmitry Safonov <dima@xxxxxxxxxx> wrote: > > > > 1. It will double copy netlink messages, making it O(n) instead > > of > > > > O(1), where n - is number of bind()s.. Probably we don't care > > much. > > > > > > About those bind() patches, I don't understand why they are > > needed. > > > > > > Why can't you just add the compat skb to the native skb when > > doing > > > the multicast call? > > > > > > skb_shinfo(skb)->frag_list = compat_skb; > > > xfrm_nlmsg_multicast(net, skb, 0, ... > > > > Oh yeah, sorry, I think I misread the patch - will try to add > > compat > > skb in the multicast call. > > -- Thanks, Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kselftest" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
